title: A synthetic peptide derived from staphylokinase enhances plasminogen activation by tissue-type plasminogen activator.
abstract: BACKGROUND
  A synthetic nonadecapeptide (SP; GPYLMVNVTGVDGKGNELL) previously enhanced the activation of plasminogen by the SAK/plasmin complex.
  
  
  OBJECTIVE
  To identify the binding site for SP on plasminogen and elucidate the effects of SP on plasminogen activation by the tissue-type plasminogen activator (t-PA).
  
  
  METHODS
  The effects of SP on plasminogen activation were estimated using a chromogenic substrate and from the cleavage of plasmin on SDS-PAGE under reduced conditions. The binding to SP of various peptides derived from the amino acid sequence of plasminogen was analyzed with an IAsys biosensor. The SP-mediated structural change to plasminogen was analyzed by circular dichroism (CD) spectroscopy. The thrombolytic effects of SP were examined using a mouse model of thrombosis.
  
  
  RESULTS
  SP enhanced the activation of plasminogen by t-PA. The catalytic efficiency (k(cat)/K(m)) of Glu-plasminogen activation by t-PA was 11.4-fold higher in the presence than absence of SP. The binding of SP to plasminogen was greatly inhibited by a synthetic peptide, FEKDKYILQGVTSWGLG, located close to the C-terminal of the plasminogen B region. Near-ultraviolet CD spectra of the complex between SP and Glu-plasminogen significantly differed from those of Glu-plasminogen. When SP was administered in a mouse model of thrombosis, early recanalization was observed in a dose-dependent manner. However, SP did not cause recanalization in t-PA gene-deficient mice.
  
  
  CONCLUSIONS
  SP bound to the B region and promoted the activation of plasminogen by t-PA, and then induced effective thrombolysis.
authors.affiliation: Department of Physiology, Kinki University School of Medicine, Osakasayama, Osaka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Okada
authors.forename: S
authors.initials: S
authors.lastname: Ueshima
authors.forename: H
authors.initials: H
authors.lastname: Matsuno
authors.forename: N
authors.initials: N
authors.lastname: Nagai
authors.forename: N
authors.initials: N
authors.lastname: Kawao
authors.forename: M
authors.initials: M
authors.lastname: Tanaka
authors.forename: O
authors.initials: O
authors.lastname: Matsuo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002942:Circular Dichroism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D042783:Endothelial Cells / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008666:Metalloendopeptidases / Q000737:chemistry*; D051379:Mice; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D010958:Plasminogen / Q000737:chemistry*; D011485:Protein Binding; D015912:Thrombolytic Therapy; D013927:Thrombosis / Q000378:metabolism; D010959:Tissue Plasminogen Activator / Q000378:metabolism*
chemical_list: D010455:Peptides; D010958:Plasminogen; D010959:Tissue Plasminogen Activator; D008666:Metalloendopeptidases; C022653:auR protein, Staphylococcus aureus